You could always have a militant or paranoid race...
With mine, I was bent on terraforming my universe to perfection, and stacked up 3000 mines to keep the AIs from bothering me while I did it.
All that research into planet improvement left me with a huge military deficit, and my LCs had to go on some tech raids against the ever-present dreadnoughts roaming the badlands beyond the minefields. And all with the minesweepers continually bashing away at the fields, providing that countdown to Doom.
[ June 18, 2003, 19:09: Message edited by: Suicide Junkie ]